The long-term objectives of the proposed research are to determine the efficacy of solubilized components of the leptomeningeal extracellular matrix in treating malignant brain tumors. Phase I feasibility studies will concentrate on 1) preparing and characterizing fibronectin from human leptomeningeal fibroblasts, 2) using that fibronectin to determine whether it can inhibit cells from causing tumors by in vitro treatment of the cells prior to injecting them, 3) whether it, like the ECM itself, can cause glioma cells to redifferentiate, and if so, to become less able to grow into tumors in vivo, and 4) test the feasibility of developing a simple mouse model system for studying metastasis within the CNS.